The present invention relates to a sphygmomanometer and, more particularly, to a valve assembly for a sphygmomanometer which controls the inflation and deflation of a pressure cuff.
Traditionally, sphygmomanometers measure blood pressure through the use of a bellows which forces air or other fluid through a valve assembly to inflate a pressure cuff. Blood pressure is measured by slowly decreasing the pressure in the pressure cuff (deflating the pressure cuff) and noting the pressures at which sounds characteristic of systolic and diastolic pressures are heard by an operator using a stethoscope. Conventionally, this cuff inflation and the slow decrease in pressure is controlled by the valve assembly, which allows air or other fluid flowing back from the pressure cuff to slowly be metered out of the valve assembly.
Generally, these valve assemblies provide a positional mechanism for the release of pressure from the pressure cuff. Normally, there is a fast vent position, for rapidly deflating the pressure cuff after systolic and diastolic pressures have been determined, and a metered deflation position, for slowly deflating the pressure cuff while systolic and diastolic pressure measurements are being taken. The fast vent and metered deflation positions, usually, are manually set, often requiring considerable manual dexterity or two-handed manipulation. Setting positions for the pressure release mechanism are normally variable with no way to positively locate the fast vent and metered deflation positions, hence, the metering rate may vary from reading to reading and from operator to operator, thereby creating inconsistencies in blood pressure measurements.
Additionally, conventional valve assemblies often use spring devices or disc type devices as check valves to prevent the leakage of air or other fluid from the pressure cuff back into the bellows. These devices do not provide a positive shut off of the air or other fluid flow other than by fluid force. Therefore, some leakage into the bellows may occur. This leakage detracts from the efficiency of cuff inflation and the consistency of blood pressure measurements. Furthermore, these conventional check valves may require the application of significant pressure to be opened such that air or other fluid may flow from the bellows to the pressure cuff. As a result, the efficiency of cuff inflation may be hindered.
Accordingly, it would be desirable to provide a valve assembly for a sphygmomanometer which would allow more consistent blood pressure measurements to be taken while eliminating the need for manual dexterity in setting the pressure release mechanism, thereby, enhancing medical industry standards and making it easier for laymen to take accurate blood pressure measurements.